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Section 7
Limit Lines and Pass/Fail Testing: Creating a Mask with Limit Lines
In many onsite test situations, it is necessary to quickly test a signal to see
whether or not it meets a specifi cation for frequency and amplitude. For
example, during radio transmitter service and maintenance, the technician
would want to make sure that the center frequency of a carrier and its harmonic
fall within a certain frequency and amplitude mask.
Limit lines make it easy to set up pass/fail testing. The analyzer compares
trace data to a set of amplitude and frequency parameters while the analyzer is
sweeping the measurement range.
Instruction
Key strokes
Connect the signal to the RF IN connec-
tor. Set center frequency and span.
[Preset], [FREQ], {Center Freq},
[100], {MHz}, [Span], [1], {MHz}
Quit digital edit state.
[ESC/CLR]
Open the limit menu.
[Limit]
Activate the limit lines.
{Limit {On}}
Open the limit lines edit menu.
{Edit Limits}
There are two ways to edit limit lines:
limit points and limits table.
{Limits Table}
Edit the point 0.
{Frequency}, [99.5] {MHz}, {Ampli-
tude}, [48], {–dBm}
Note: For other points, you only need to press {Add} and enter the frequency and amplitude.
Firmware above A.01.02 will support 100 limit points.
Figure 4. FM signal with limit lines
